Not every sexuality and gender (or non-gender) is listed on the Genderbread picture. It is a spectrum, and whoever made the picture was obviously just thinking of it in terms of a scale, while many people may not even be on the scale at all.
It’s easy to take off your clothes and have sex. People do it all the time. But opening up your soul to someone, letting them into your spirit, thoughts, fears, future, hopes, dreams… that is being naked.